Making standard ML a practical database programming language

Abstract

Integrating a database query language into a programming language is becoming increasingly important in recently emerging high-level cloud computing and other applications, where efficient and sophisticated data manipulation is required during computation. This paper reports on seamless integration of SQL into SML# - an extension of Standard ML. In the integrated language, the type system always infers a principal type for any type consistent SQL expression. This makes SQL queries first-class citizens, which can be freely combined with any other language constructs definable in Standard ML. For a program involving SQL queries, the compiler separates SQL queries and delegates their evaluation to a database server, e.g. PostgreSQL or MySQL in the currently implemented version.